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Home >> Lexus >> 2008 >> IS F >> Repair and Diagnosis >> Engine Performance >> System >> Engine Control System - SFI System Diagnostics (3 Of 4) >> DTC P050A Cold Start Idle Air Control System Performance >> Inspection Procedure
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Inspection Procedure

HINT.

Read freeze frame data using the Techstream The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

  1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P050A) 
    1. Connect the Techstream to the DLC3.
    2. Turn the engine switch on (IG).
    3. Turn the Techstream ON
    4. Enter the following menus: Powertrain / Engine / Trouble Codes
    5. Read the DTCs

      Result 

      RESULT CHART

      Result Proceed to
      DTC P050A is output A
      DTC P050A and other DTCs are output B

      HINT.

      If any DTCs other than P050A are output, troubleshoot those DTCs first.

    B: GO TO DTC CHART  (See DIAGNOSTIC TROUBLE CODE CHART )

    A: Go to next step 

  2. READ VALUE USING TECHSTREAM (FUEL TRIM) 

    HINT

    Calculate the total fuel trim values to check the characteristic deviation of the mass air flow meter.

    1. Connect the Techstream to the DLC3.
    2. Start the engine.
    3. Turn the Techstream ON
    4. Enter the following menus Powertrain / Engine / Data List / Short FT #1 and Long FT #1, or Short FT #2 and Long FT #2.
    5. Read the values displayed on the Techstream at engine idle.
    6. Add together the Short FT #1 and Long FT #1, or Short FT #2 and Long FT #2 values to obtain the total Fuel Trim

      OK: Total of Short FT #1 and Long FT #1, or Short FT #2 and Long FT #2 values is between -20% and 20%. 

      Result 

      RESULT CHART

      Result Proceed to
      NG A
      OK B

    B: Go to step  12

    A: Go to next step 

  3. PERFORM ACTIVE TEST USING TECHSTREAM (CONTROL THE MD VVT LINEAR) 
    1. Connect the Techstream to the DLC3
    2. Turn the engine switch on (IG) and turn the Techstream ON
    3. Start the engine and warm it up
    4. Enter the following menus Powertrain / Engine / Active Test / Control the VVT-iE Linear (Bank 1) or Control the VVT-iE Linear (Bank 2) / VVT-iE Aim Angle (Bank 1) and MD VVT Change Angle (Bank 1) or VVT-iE Aim Angle (Bank 2) and VVT-iE Change Angle (Bank 2)
    5. Perform the Active Test operation with the engine speed at 1500 rpm

      OK 

      ACTIVE TEST

      Active Test Movement Order Difference between "VVT-iE Aim Angle" and "VVT Change Angle"
      0 deg → 10 deg → 20 deg → 40 deg → 10 deg → 0 deg → 10 deg → END Within 4 DegFR

    NG: Go to step  8

    OK: Go to next step 

  4. CHECK PCV HOSE CONNECTIONS 
    1. Inspect PCV hose connection (See ON-VEHICLE INSPECTION )

      OK: PCV hose is connected correctly and is not damaged. 

    NG: Go to step  9

    OK: Go to next step 

  5. CHECK INTAKE SYSTEM 
    1. Check the intake system for vacuum leaks (See ON-VEHICLE INSPECTION ).

      OK: No leaks from intake system. 

    NG: Go to step  10

    OK: Go to next step 

  6. CHECK AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY 
    1. Visually check that the air cleaner filter element is not excessively contaminated with dirt or oil.

      OK: Air cleaner filter element is not excessively contaminated with dirt or oil. 

    NG: Go to step  11

    OK: Go to next step 

  7. REPLACE MASS AIR FLOW METER 
    1. Replace the mass air flow meter (See REMOVAL )

    NEXT: Go to step  15

  8. CHECK AND REPAIR VVT SYSTEM 
    1. Check and repair VVT system

    NEXT: Go to step  15

  9. REPAIR OR REPLACE PCV HOSE 
    1. Repair or replace PCV hose (See ON-VEHICLE INSPECTION )

    NEXT: Go to step  15

  10. REPAIR OR REPLACE INTAKE SYSTEM 
    1. Repair or replace intake system (See REMOVAL )

    NEXT: Go to step  15

  11. REPLACE AIR CLEANER FILTER ELEMENT SUB-ASSEMBLY 
    1. Replace air cleaner filter element sub-assembly.

    NEXT: Go to step  15

  12. CHECK THROTTLE VALVE 
    1. Check for deposits around the throttle valve and throttle valve condition

      OK: No deposits around throttle valve and throttle valve moves smoothly. 

    NG: Go to step  14

    OK: Go to next step 

  13. REPLACE ECM 
    1. Replace the ECM (See REMOVAL )

    NEXT: Go to step  15

  14. REPAIR OR REPLACE THROTTLE BODY ASSEMBLY 
    1. Repair or replace throttle body assembly (See REMOVAL )

    NEXT: Go to step 15 

  15. CHECK WHETHER DTC OUTPUT RECURS (DTC P050A) 
    NOTE: In this operation, the engine must be cold (the same level as the engine coolant temperature recorded in the freeze frame data).
    1. Connect the Techstream to the DLC3
    2. Turn the engine switch on (IG).
    3. Turn the Techstream ON
    4. Clear DTCs (See DTC CHECK/CLEAR ).
    5. Switch the ECM from normal mode to check mode using the Techstream (See CHECK MODE PROCEDURE ).
    6. Start the engine to idle for a minute

      OK: Stable fast idling. 

    7. Read the DTCs.

      OK: No DTC output. 

    NEXT: END